Studies have demonstrated that both the risk of coronary heart disease (CHD) in humans and the severity of experimental atherosclerosis in animals are inversely correlated with serum high density lipoprotein cholesterol (HDL-C) concentrations (see, eg, Russ et al, Am. J. Med., 11 (1951) 480–493; Gofman et al, Circulation, 34 (1966) 679–697; Miller and Miller, Lancet, 1 (1975) 16–19; Gordon et al, Circulation, 79 (1989)8–15; Stampfer et al, N. Engl. J. Med., 325 (1991) 373–381; and Badimon et al, Lab. Invest., 60 (1989) 455–461). Atherosclerosis is the process of the accumulation of cholesterol within the arterial wall which results in the occlusion or stenosis of coronary and cerebral arterial vessels and subsequent myocardial infarction and stroke. Angiographical studies have shown that elevated level of some HDL particles in humans appears to be correlated to a decreased number of sites of stenosis in the coronary arteries of humans (see, eg, Miller et al, Br. Med. J., 282 (1981) 1741–1744).
There are several mechanisms by which HDL may protect against the progression of atherosclerosis. Studies in vitro have shown that HDL is capable of removing cholesterol from cells (see, e.g., Picardo et al, Arteriosclerosis, 6 (1986) 434–441). Data of this nature suggest that one antiatherogenic property of HDL may lie in its ability to deplete tissues of excess free cholesterol and eventually lead to the delivery of this cholesterol to the liver (see, e.g., Glomset, J. Lipid Res., 9 (1968) 155–167). This has been supported by experiments showing efficient transfer of cholesterol from HDL to the liver (see, eg, Glass et al., J. Biol. Chem., 258 (1983) 7161–7167; MacKinnon et al, J. Biol. Chem., 261 (1986) 2548–2552). In addition, HDL may serve as a reservoir in the circulation for apoproteins necessary for the rapid metabolism of triglyceride-rich lipoproteins (see, eg, Grow and Fried, J. Biol. Chem., 253 (1978) 1834–1841; Lagocki and Scanu, J. Biol. Chem., 255 (1980) 3701–3706; and Schaefer et al, J. Lipid Res., 23 (1982) 1259–1273). Accordingly, agents which increase HDL cholesterol concentrations are useful as anti-atherosclerotic agents, particularly in the treatment of dyslipoproteinemias and coronary heart disease.
European Patent No. 718290-A1 claims carboxyalkyl heterocyclic derivatives as aldose reductase inhibitors useful in treating diabetic complications. Among compounds claimed are 4,5-dioxo-1-thioxoimidazolidines of the following formula:
wherein:                R is hydrogen or lower alkyl of 1–3 carbon atoms;        n is an integer of 1–3; and        X is benzyl, benzothiazolylmethyl, or naphthyl methyl        
U.S. Pat. No. 5,312,919 claims the preparation and use of merodantoin (1) as anticancer and antiviral agents. The patent further discloses compounds of formula 2:
where R1 and R2 may be                hydrogen, C1–C6 alkyl, or benzyl        
U.S. Pat. Nos 4,084,001 and 4,152,453 claim the use of compounds of formula (1) as intermediates in the preparation of histamine blocking agents and as inhibitors of acid secretion (2).
wherein:                R is alkyl and        n is an integer of 1–6.        
U.S. Pat. No. 3,461,133 discloses compounds of the following formula as herbicides:
wherein:                R is an alkyl of 1–12 carbon atoms, alkenyl, or alkynyl.        
German Patent DE 3540919 claims compounds of the following formula as herbicidal agents:
wherein:                R1 is hydrogen, alkyl; and        R2 is alkyl, phenyl, or phenylalkyl.        
German Patent DD 154819 discloses methods for the preparation of compounds of formula (1) from 4,5-di-imino compounds (2)

German Patent DD 219483 A1 discloses compounds of the following formula as antitubercular agents:
wherein:                R is aryl; and        n is an integer of 1–2.        